In general, a bill processing apparatus, which processes a bill as one of the embodiments of a paper sheet or the like, is incorporated into a service device such as a game medium rental machine installed in a game hall, a vending machine or a ticket-vending machine installed in a public space, or the like which identifies the authenticity of a bill inserted from a bill insertion slot by a user and provides various types of products and services in accordance with a value of the bill having been judged as authentic.
Usually, the authenticity of the bill is identified by a bill identification apparatus installed in a bill traveling route provided so as to connect to a bill insertion slot. The bill moving inside the bill traveling route is irradiated with light, and a transmitted light or a reflected light therefrom is received by a light receiving sensor, and the received light data is compared with the legitimate data to identify the authenticity of the bill.
Meanwhile, various innovations have been devised for bills in order to prevent counterfeiting thereof. As one of those, a watermark with an uneven portrait is formed by a special technique, or a see-through patterned mark which can be determined as authentic or counterfeit with a tactile sense is formed (hereinafter, watermarks formed on bills or see-through patterning are collectively referred to as “watermark”). Such a watermark may be utilized as an authenticity identification object area in order to improve the identification accuracy of the authenticity of the bill. In Patent reference 1, for example, a bill discrimination device is disclosed, which discriminates the authenticity of the bill by irradiating infrared light and visible light to a watermark and acquiring transmitted light and reflected light therefrom.
Further, in Patent reference 1, a technology to improve the identification accuracy of the authenticity is disclosed, in which a presser part that presses a bill is installed in the apparatus in consideration of wrinkle existence on the bill being inserted into a bill insertion slot and the bill is pressed by the presser part to smooth the wrinkles out of the bill, whereby the identification accuracy of the authenticity may be improved.    [Patent reference 1] Japanese unexamined patent application publication No. 2006-285775